El Niño, Global Weather Pattern Tied to Intense Heat, Is Expected by Fall

Forecasters from the World Meteorological Organization are reporting increased chances that the global climate pattern known as El Niño will arrive by the end of summer. With it comes increased chances for hotter-than-normal temperatures in 2024.

While there is not yet a clear picture of how strong the El Niño event will be or how long it might last, even a relatively mild one could affect precipitation and temperature patterns around the world.

“The development of an El Niño will most likely lead to a new spike in global warming and increase the chance of breaking temperature records,” said Petteri Taalas, the general secretary of the meteorological organization, in a news release.

El Niño is associated with warmer-than-normal ocean surface temperatures in the central and eastern tropical Pacific Ocean. In the United States, it tends to lead to rainier, cooler conditions in much of the South, and warmer conditions in parts of the North.

Elsewhere, El Niño can bring increased rainfall to southern South America and the Horn of Africa, and severe drought to Australia, Indonesia and parts of southern Asia.

El Niño, together with its counterpart La Niña, is part of the intermittent cycle known as the El Niño-Southern Oscillation, or ENSO, that is highly influential in shaping year-to-year variations in weather conditions across the globe.

ENSO is a naturally-occuring phenomenon, and scientists are still researching exactly how human-caused climate change over the past 150 years may be impacting the behavior and dynamics of El Niño and La Niña events, with some studies suggesting that El Niño events may be more extreme in a warmer future.

Conditions in the tropical Pacific have been in a neutral state since the latest La Niña event ended this year. La Niña conditions had persisted through a rare three consecutive winters in the Northern Hemisphere, supercharging Atlantic hurricane seasons and prolonging severe drought across much of the Western United States.

Yet, despite the cooling effect La Niña typically has, the last eight years have been the hottest on record, a worrisome addition to the longer-term pattern of temperatures that have been steadily rising as the world continues to emit greenhouse gases from burning coal, oil and natural gas.

According to the World Meteorological Organization outlook, there is about a 60 percent chance that El Niño will form between May and July, and an 80 percent chance it will form between July and September. The forecasts are based on observations of wind patterns and ocean temperatures as well as climate modeling, said Wilfran Moufouma-Okia, head of the Climate Prediction Services Division at the organization, which is a United Nations agency.

The National Oceanic and Atmospheric Administration issued a similar outlook last month. Both groups cautioned that while El Niño events are associated with certain typical conditions, they unfold differently each time. But in general, the warmest year of any decade will be an El Niño year, and the coldest a La Niña one, according to data from NOAA’s National Centers for Environmental Information.

Research around global warming’s effects on precipitation and temperature worldwide are much more conclusive: It has intensified wet and dry global extremes, prolonged hot waves and warmed winters.

“There’s little doubt that El Niño loads the dice in favor of higher global mean temperatures,” said Michelle L’Heureux, a climate scientist with NOAA’s Climate Prediction Center.

But, separately, climate change has led to global temperatures that are, on average, warmer over time, she said, and the combination of both could lead to more record-breaking temperatures.